Introduction

A well-built retaining wall is essential for maintaining the stability of your landscape and preventing erosion. However, many contractors make common mistakes and cut corners that can compromise the integrity and longevity of a retaining wall. To ensure your wall stands the test of time, avoid these critical errors.

1. Footer not Deep Enough

One of the most crucial aspects of a retaining wall is its foundation. A proper base should consist of at least 6 inches of compacted gravel or #57 stone to provide stability and drainage. Skimping on the base depth can lead to settling, shifting, or even wall failure over time.

2. Improper Compaction of the Base Material

Even with the right base material, improper compaction can cause significant issues. The base layer must be compacted in small increments using a plate compactor to create a solid foundation. Poor compaction can result in an uneven base, leading to leaning or collapsing walls.

3. Blocks Not Leveled

The first row of blocks is the most important. If the blocks are not perfectly level left to right and front to back, the imperfections will compound as the wall gets taller. A wall that leans too far back, outward, or appears uneven is often the result of poor leveling at the base. Taking extra time to ensure the first course is flawless will save headaches later on.

4. No Core Fill

For walls using hollow-core blocks, filling the cores with gravel adds weight, stability, and better drainage. Skipping this step can result in a weaker wall that is more susceptible to shifting and failure over time. All blocks must be filled. 

5. Insufficient Drainage Backfill

Water buildup behind a retaining wall is one of the leading causes of failure. To allow for proper drainage, there should be at least 12 inches of gravel backfill behind the wall. Without sufficient drainage, hydrostatic pressure can push against the wall, causing bulging or collapse.

6. No Geo-Grid

Walls over 4 feet tall or supporting additional weight (such as a driveway or slope) require geo-grid reinforcement. This geosynthetic material extends into the soil behind the wall, increasing stability and preventing outward movement. Failing to use geo-grid in these situations can lead to wall failure over time.

7. Too Much Water

Retaining walls are designed to hold back soil, not water. Without proper drainage solutions, such as drain pipes, grading, and swales, excess water can weaken the structure. Ensuring water is directed away from the wall will help maintain its strength and longevity.

Conclusion

Avoiding these common mistakes will help you build a retaining wall that is structurally sound and long-lasting. Proper planning, material selection, and attention to detail are key to ensuring your wall remains intact for years to come. If you’re unsure about any aspect of your retaining wall project, Redwood Lawn and Landscape can help. Contact us today for expert installation and guidance!